SIP Trunk

Sip Trunk

You are buying a new TC system for your company. How do you make calls? Via ISDN or Voice over IP? You won’t be able to get around answering this question in the medium and long term.

SIP Trunks will ultimately replace the classical ISDN connections, namely, when new orders for ISDN stop being accepted starting in 2016 and no later than 2018, when ISDN will be permanently shut off.

With a SIP Trunk, you manage a direct dialing-capable number in contrast to SIP accounts with which only individual numbers (no number block!) can be assigned to extensions.

Simply stated: SIP Trunks replace any kind of direct dialing-capable system connections (such as S0 AnAs and S2M PMX) and SIP accounts replace the classical ISDN multi-device connections (no analog services!).

SIP Trunks are suitable for companies of any size since, in contrast to SIP accounts, they can be managed and assigned in complete number blocks with 10, 100, 1000 and 10,000 numbers.

Depending on the provider, they can be expanded from the current 30 channels to up to 300 or more channels.

The principle is very simple. Your phone number is still assigned by a provider which bills you on the basis of x amount of minutes or a flat rate model. The actual change with SIP Trunks in comparison to classical ISDN is that you no longer require a voice line via which you place calls, but any number of dimensioned data lines allow for this functionality.

In general, 100kbit/s upload are reserved per call.

Overview of all providers

Provider	Product
	Colt VoIP Access
	QSC IPfonie extended + IPfonie extended Link
	Ecotel Sip Trunk DDI
	Versatel VT ngn

Costs for an SIP Trunk

The costs for SIP Trunks are significantly lower in comparison to classical connections.

While you can get a system connection (for 2 simultaneous calls) starting from approx. 18€ per month, SIP Trunk starts at 1.40€ per month for one call.

This is however only half the truth. You will certainly require more than one channel and the providers are not united on this. Depending on the model, you receive your SIP Trunks in packets (i.e. in steps of 10 or 50) or only conjunction with data lines.

Furthermore, the providers are always throwing different promotions on market in order to gain new customers which makes a blanket statement regarding costs impossible. In general, the following points must be clearly defined in order to make a valid statement regarding providers and conditions:

• Number of channels
• Contract duration
• Volumes/rates
• Encryption
• Rate model
• Is a data line also required?
• What kind of data line?